The present invention relates to the improvement of spring needle circular knitting machines utilizing a lay-in concept and, in particular, to an improved construction for clearing lay-in yarn over tie yarn within each feed section of the machine.
Spring needle knitting machines are well known in the art. These machines have enjoyed great longevity because of their rugged construction and their ability to produce any number of fabric constructions such as fleece, terry, plush, pile and the like using what is generally referred to as the "lay-in concept". This concept basically involves bringing together or knitting one or more lay-in yarns with a tie or binder yarn and a stitch yarn. This concept is embodied in machines of the general type manufactured by Tompkins Brothers Co., Inc., Syracuse, N.Y. and illustrated in U.S. Pat. No. 475,058 to Hill and U.S. Pat. No. 1,805,339 to McAdams and the disclosure in these patents may be considered as being incorporated herein by reference for background purposes.
In the spring needle machine, a cylinder of vertically disposed, equally spaced needles are rotated past one or more feed stations that are capable of adding a complete course of yarn to the fabric. Normally, a number of feed stations are positioned about the needle cylinder so that several courses can be added to the fabric during each complete revolution of the cylinder. As can be seen, if the circumferential length of each feed station can be compressed or reduced, more stations can be added to the machine thus increasing its productivity.
Ordinarily, after the lay-in yarn has been placed in front and behind the shanks of the needles and cleared downwardly, tie yarn is looped underneath the open beards of the needle. The beards are then closed using either a stationary, horizontally aligned bar or a presser wheel of the type disclosed by Logan in U.S. Pat. No. 2,187,132. After closure, the lay-in yarn is raised by means of an independent lander burr over the closed needles to intertwine the two yarns. As should be evident, the sinker burr, the presser device and the lander burr, all being separately mounted in the feed station, utilize a relatively large amount of the overall feed length. By the same token, because all the elements are separately mounted, they each must be accurately positioned and secured in relation to each other to insure that the course is properly knitted. Any misalignment or movement of an element within the feed will result in the production of unusable fabric. For instance, if the presser device does not close the beards almost immediately after the tie loop is introduced thereunder, the tie yarn can fall out of the beards before the lay-in yarn is landed thus placing a defect in the fabric.
In U.S. Pat. No. 2,286,469 to Crommie, there is disclosed a feed station for use in a circular knitting machine having a combined beard closing disc and stitch cast-off wheel that are mounted upon a single spindle. The device basically includes a conventional bladed cast-off wheel and a flat faced washer that is held against the upstream end face of the cast-off wheel. The outer periphery of the washer is generally perpendicular to its flat end face. Accordingly, when the periphery of the washer is rotated with the bladed wheel across the beards of the needles, the beards are only held closed for an extremely short period of time. The opening and closing action of the washer is sometimes completed before the bladed wheel has a chance to contact the previously formed stitch. As a consequence, the beards are opened or partially opened as the yarn begins to move thereover. It has also been found that the flat contoured washer arrangement produces a less than smooth beard closing action and can overstress the beards thus leading to early failure of the needles.
As noted, in the Crommie device the beard closing washer is mounted upon the same spindle as the cast-off wheel. The washer is held to the spindle by a nut that is threaded onto the end of the spindle. The nut protrudes a considerable distance out from the end face of the washer and thus does not permit the adjacent feed element to be mounted in close proximity therewith. Consequently, whatever space advantage that might have been gained by mounting the beard closing washer upon the same spindle can very well be lost because of the bulky mounting structure. This, combined with the inability to coordinate the activity of the beard closing washer with that of the cast-off wheel, has resulted in the washer type combination not finding widespread use in the industry.